Apparatus and method for the power management of operatively connected batteries respectively on a handheld electronic device and a holder for the handheld electronic device

ABSTRACT

A handheld electronic device in conjunction with a holder for the handheld electronic device that together form an electronic device. The handheld electronic device includes a first battery and the holder includes a second battery and a charging apparatus. When the handheld electronic device and the holder are electrically connected together, such as when the handheld electronic device is received in a cavity formed in the holder the charging apparatus charges the first battery on the handheld electronic device from the second battery on the holder when the first battery charge has been depleted to a given level and the second battery charge is above a second given level. Alternatively, if the first battery charge is above a third given level the first battery charges the second battery if the second battery is not fully charged.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. application Ser. No.12/470,717, entitled “Apparatus and Method for the Power Management ofOperatively Connected Batteries Respectively on a Handheld ElectronicDevice and a Holder for the Handheld Electronic Device”, filed on May22, 2009, which is a continuation of U.S. application Ser. No.11/556,547, entitled “Apparatus and Method for the Power Management ofOperatively Connected Batteries Respectively on a Handheld ElectronicDevice and a Holder for the Handheld Electronic Device”, filed on Nov.3, 2006, which has issued as U.S. Pat. No. 7,554,289, both of which areincorporated herein by reference.

BACKGROUND

1. Field

This device and method relate generally to handheld electronic devicesand, more particularly, to an electronic device having an on boardbattery that shares charge with a second battery in a holster. Thedevice and method described herein also relate to a method of sharingcharge between a battery on a handheld electronic device and a secondbattery in a holster for holding the handheld electronic device.

2. Background

Numerous types of handheld electronic devices are known. Examples ofsuch handheld electronic devices include, for instance, personal dataassistants (PDAs), handheld computers, two-way pagers, cellulartelephones, and the like. Such handheld electronic devices are generallyintended to be portable and thus are small and battery powered. Whilesome handheld electronic devices include a wireless communicationcapability, other handheld electronic devices are stand alone devicesthat do not communicate with other devices.

A battery of a handheld electronic device typically constitutes asignificant portion of the weight of the handheld electronic device.While it is often desirable to reduce the weight and shrink the formfactor of a handheld electronic device, it is nevertheless necessary toprovide sufficient battery power and capacity to enable the handheldelectronic device to function properly for an appropriate duration oftime. Power consumption can be of particular importance in handheldelectronic devices having a wireless capability that complies withGPRS/GSM operating guide lines, since a power amplifier of such ahandheld electronic device can have a peak current requirement of up toabout 2.5 amperes during transmission bursts.

It would be desirable to provide an improved handheld electronic devicehaving a reduced weight and/or a smaller form factor than currentlyknown devices without sacrificing battery power or battery life.

BRIEF DESCRIPTION OF THE DRAWINGS

A further understanding of the device and method disclosed herein can begained from the following description of the preferred embodiments whenread in conjunction with the accompanying drawings in which:

FIG. 1 is an isometric view of an improved electronic device inaccordance with the embodiments described herein that includes animproved handheld electronic device and an improved holder;

FIG. 2 is an exploded isometric view of the improved electronic deviceof FIG. 1;

FIG. 3 is an isometric view of an improved electronic device inaccordance with another embodiment described herein;

FIG. 4 is a block diagram of the electronic device of FIG. 1;

FIG. 5 is a block diagram of the electronic device in accordance withanother embodiment described herein;

FIG. 6 is a logic flow chart of the operation of the handheld electronicdevice described herein;

FIG. 7 is a block circuit diagram of the charging circuit of thehandheld electronic device described herein;

FIG. 8 is a logic flow chart of the circuitry of the holder of thedevice described herein;

FIG. 9 is a block circuit diagram of the holder charging circuit of thedevice described herein.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

An improved electronic device 4 is indicated generally in FIGS. 1 and 2.The electronic device 4 includes an improved handheld electronic device8 and an improved holder 12. The holder 12 cooperates with the handheldelectronic device 8, as will be set forth in greater detail below.Examples of handheld electronic devices are disclosed in U.S. Pat. Nos.6,452,588 and 6,489,950.

The handheld electronic device 8 includes a housing 16, a display 20, aprocessor 24, a keyboard 28, and a first battery 32. The processor 24can be any of a wide variety of processors, such as, without limitation,a microprocessor (μP). The processor 24 is operable to receive inputsfrom the keyboard 28 and to provide processed output to the display 20.The first battery 32 provides power to the processor 24 and the display20. The handheld electronic device 8 additionally includes a pluralityof contacts 36 that are disposed on the housing 16 and are electricallyconnected with the battery 32.

The holder or holster 12 includes a housing 40 formed with a cavity 44,a first charging apparatus 48, a second battery 52 and a second chargingapparatus 56 (shown in FIG. 4). The first charging apparatus 48 and thesecond charging apparatus 56 are both electrically connected with thesecond battery 52. The holder 12 additionally includes a plurality ofsecond contacts 60 (FIG. 4) disposed on the housing 40 within the cavity44 and, in the embodiment depicted in FIGS. 1 and 2, includes a powercord 64 that is electrically connectable with a suitable external powersource 68 (FIG. 4) which, in the present example, is a 110 volt AC powersource, though, as will be appreciated in the art, the external powersource 68 may also be a USB port. The second contacts 60 areelectrically connectable with the first contacts 36 of the handheldelectronic device 8. The housing 40 includes an opening 72 formedtherein that enables the user to gain access to the keyboard 28 andobserve the display 20 when the handheld device 8 is received in a firstorientation (FIG. 1) in the housing 40.

The embodiments described herein address the limited battery life ofhandheld devices by supplementing the charge stored in the handheldbattery 32 with charge stored in an additional battery 52 built into theholder or holster 12 through the built in charging contacts 36 of thehandheld electronic device 8 and the built in mating charging contacts60 of the holder 12. The embodiments described herein also do away withthe problem of a user charging and carrying two separate batteries byeffectively hiding the second battery 52 within an accessory, in thiscase the holster 12. New flexible battery technologies will allow thesecondary battery to be built into plastic holsters or be woven intoleather holsters.

Thus the embodiments described herein include a second battery 52 sealedwithin the holster or holder 12 to provide additional charge to theprimary handheld battery 32 through the charge contacts 36 and 60 shouldthe primary battery 32 fall below a preset charge level. Included aspart of the device and method described herein is an algorithm whichcontrols the charging and discharging of the secondary battery 52without the use of charging port 64 on the holster 12. Thus, the objectof this embodiment is to have a battery 52 in the holster 12 that willact to supplement the device battery 32, thereby increasing the apparentoperating time of the device. Several factors are additionallycontemplated to make the added capability of the device described hereinmore attractive to the user. In the first instance the holster battery52 should be thin so as not to make the holster 12 bulky. Li-polymercells satisfy this criterion. They can be made very thin, and yet have avery large area (for increased energy storage capacity), and they arequite flexible. Secondly, the modifications to the device should beminimal. Thirdly, the brunt of the cost of the modification should beborne by the holster side 12 so as not to saddle those users that don'twant to bear the cost of this improvement. Fourthly, the holster battery52 should meet all safety requirements.

In a first preferred embodiment the secondary battery 52 would be afraction of the size of the primary battery 32, i.e. about 30%. Thiswill, in most instances, permit a user to obtain an additional day ortwo of use before the handheld electronic device has to be rechargedfrom an external source. It is known that longer battery life improvesthe user's experience. Unfortunately, improving the technology of thebattery or providing a replaceable battery increases the device cost. Onthe other hand, providing a higher capacity battery would increase theweight and size factors. While optimize software decreases deviceconsumption it is effective up to a certain point.

In a second embodiment the secondary battery 52 in the holster 12 is atleast approximately ⅓ larger than the operational battery 32 in theelectronic handheld device 8 so that a smaller operational battery 32with a size and capacity of a about ⅓ of the current battery can beused. The operational battery 32 is installed on the handheld electronicdevice 8 to maintain it while the user is effectively working. Thesupplementary or secondary battery 52 is integrated in the holster 12.While the device 8 is in the holster 12 it would consume power from thesupplementary battery 52 through power connectors 36 and 60 located inthe bottom or back of the handheld electronic device 8. The operationalbattery 32 would be charged at the same time through these same contacts36 and 60. For some applications, the average device is in its holsterapproximately 95% of the time so the capacity of the operational batterythat is residing on the device does not need to be as high. On the otherhand, the battery residing on the holster can be extended in capacitysince its weight would not contribute to the handheld device's weightunder this arrangement. If you take the battery out of a handheldelectronic device such as the BlackBerry device and hold the device inyour hand it feels surprisingly light. The BlackBerry device itselfweighs 136 grams. The battery adds an additional 26 grams to the weight.Thus, in this embodiment the weight can be minimized while extending thebattery life.

Under either arrangement the user would need to charge only the holster.The battery 32 residing on the handheld electronic device 8 would chargeitself from the holster's battery 52. Moreover, the battery 32 on thehandheld electronic device 8 does not need to be removable. When thebattery 52 on the holster 12 is discharged and the user wants to gethis/her device working right away then he/she just takes anotherholster—a procedure much easier than changing the battery (and thedevice will not even be restarted). In this way an effective removablebattery is achieved in a more cost effective and user friendly way. Atthe same time the overall battery life of the device can be improved andthe weight of the device can be decreased. Whether the larger of the twobatteries 32 and 52 is incorporated in the holder 12 or handheld device8 will depend on the nature of the handheld device and the relativetimes the device is situated in and out of the holder 12.

Alternatively, in accordance with another embodiment, if the handheldelectronic device 8 is separately charged from an external source tosubstantially its full charge level and the secondary battery 52 on theholster 12 is below a certain level the primary battery 32 on thehandheld electronic device 8 may be used to charge the holster battery52 each time the handheld electronic device 8 is placed within itsholster. Preferably, only a preselected amount of charge, for example100 mAhr (about 10% of the capacity of a typical handheld battery istransferred from the handheld electronic device 8 to the holster battery52 each time the handheld electronic device 8 is placed within theholster 12, to conserve power in the handheld electronic device 8. Thehandheld electronic device 8 may be separately charged from an externalsource, for example, when it is placed in a docking station.

In accordance with this embodiment, the charge algorithm for theelectronic device 4 is as follows:

-   -   1. If a fully charged handheld device 8 is placed in the holster        12 with a discharged secondary battery 52, the handheld device 8        will allow the holster battery 52 to trickle charge the handheld        battery 32 through the charge contacts 36 and 60 down to a        preset point of about 3.9V, or 10% of the initial capacity, so        that the user does not notice significantly reduced battery life        in the primary battery 32. Trickle charging is defined as        charging at a small portion of the maximum specified charge rate        for a particular battery. Each time a fully charged device is        inserted within the holster 12, a preset amount of charge is        transferred from the primary battery 32 to the secondary battery        under conditions where the secondary battery is to be charged.        If the user does not recharge the handheld before the primary        battery 32 fully discharges, the holster battery 52 will return        the battery charge before the primary battery 32 is fully        discharged.    -   2. Alternatively, the algorithm allows the battery 52 in the        holster 12 to be charged when the electronic device 4 is        attached to a USB port or 110 volt external source and charge        both the primary battery 32 and the secondary battery 52 while        the handheld electronic device 8 is in the holster 12. The        charge states set forth in the above Paragraph 1 and this        Paragraph 2 may be set in a settings menu on the handheld        electronic device 8.    -   3. After several full charge insertions of the handheld        electronic device 8 into the holder 12, without drain of the        primary battery 32 below a set level, which is preferably,        substantially equal to the full charge level of the primary        battery, the secondary battery 52 will contain a full charge and        will no longer take charge from a fully charged primary battery        32.    -   4. During travel, or when the user is away from a charge source        for an extended period, and the handheld battery reaches a        preset highly discharged level, such as one bar on the screen,        the handheld electronic device 8 can request charge from the        secondary battery 52 to partially recharge the battery 32 on the        handheld electronic device 8. In this event, with a reasonable        efficiency of transfer of energy, the user may gain upwards of        one or two days of use.

FIGS. 6 and 7 respectively show the logic and circuitry modificationsthat are applied to the handheld electronic device 8 to implement thisembodiment. From FIG. 6 it can be appreciated that the device detectswhether it is holstered or not. This is readily done with handheldelectronic devices 8 such as a BlackBerry by the use of a magnetic reedswitch inside the device that detects a magnetic field generated by asmall permanent magnet inside the holster. When the handheld electronicdevice 8 is in the holster 12, the battery terminals 36 are madedirectly accessible to the electronic device “charging” pads 60.Otherwise the device charging pads act just as they would normally andthat is to be normal charging pads, such as for cradle charging. Thelogic for this operation is illustrated in FIG. 6 and a block diagram ofthe battery charging circuit for the handheld electronic device 8 isshown in FIG. 7. When the reed switch is high, that is in position A,the charging pads 36 are connected directly to the battery 32 through aprotection circuit module 76 which is an integral part of the batterypack 32. The protection circuit module 76 protects the battery on thehandheld device 8 from overcharging. When the reed switch 72 is low,that is position B the handheld electronic device 8 battery charger 48is interposed between the charging pads 36 and the battery pack 32.Thus, very little modification and expense has to be added to thehandheld electronic device 8 to implement this embodiment.

Most of the modification is made to the holster or holder 12 asillustrated in the logic flowchart shown in FIG. 8 and the circuit blockdiagram illustrated in FIG. 9. Referring to FIG. 8 it can be appreciatedthat when the handheld electronic device 8 is in the holster 12 the pads60 will be connected to the battery 32 on the handheld electronic device8 and will thus have a voltage on them. Normal Li-Ion batteries havevoltages of about 4.2 V when fully charged. These batteries plateau ataround 3.7 V-3.8 V during most of their discharge, and quickly dropduring the final stages of discharge. In fact, at about 3.3 V, the cellsof the battery contain less than 10% energy left in them. All of thesevalues are room temperature values and these room temperature valueswill be used in this embodiment. Various other schemes can also be usedto determine the state of charge of the lithium Li-Ion battery, forexample Coulomb Counting could be employed, in which the amount ofcharge required to fill a completely discharged battery is recorded andthe State of Charge, or SoC, is determined by counting the amount ofcharge dispensed. As can be seen from FIG. 8 the algorithm for holsteroperation is as follows:

-   -   1. The circuit in the holder 12 determines if the handheld        electronic device battery 32 can provide some charge to charge        up the holster battery 52. This is primarily done by measuring        the voltage of the handheld electronic device battery 32. If it        is high enough (that is around 3.8 V+, meaning that the device        battery is itself fully charged), then this condition is TRUE.        In this case an internal (to the holster 12) DC-DC        converter/charger is used to leak off some charge to charge up        the holster battery Up to 10% of the device battery's charge is        a reasonable amount to be leaked off for this purpose. The DC-DC        converter is needed because most chargers need a somewhat higher        voltage at their inputs than what they will provide at their        outputs. So, to fully charge up a Li-Ion or Lithium polymer        battery to 4.2 V, typical chargers need at least 5.0 V. Since        the power source itself is a Li-Ion battery, there is a need for        a DC-DC conversion to boost up the charger input.    -   2. If the handheld device battery 32 is in between fully charged        and near empty (between approximately 3.8 V to 3.4 V) then the        handheld electronic device 8 can neither provide charge to the        holster, nor does it need a boost from the holster and the pads        60 are disconnected from the battery 32. In this case the        battery may have reached this stage from the stage described in        Paragraph 1 above, or it may already be in this state at the        moment when it was holstered. In the first case, this stage        provides a mechanism to stop charging in accordance with        Paragraph 1 immediately above without having the holster 12        immediately switch back and forth between that set forth in        Paragraph 1 above and that provided in Paragraph 3 immediately        below.    -   3. If the handheld electronic device battery 32 is very low,        then the holster battery 52 will give back some of its charge.        The holster battery 52 itself should not give back so much of        its charge that it drains itself beyond its limits. This is        accomplished through the protection circuit module (PCM) which        prevents the holster battery 52 from over discharging and short        circuits, etc. If the holster battery has enough charge, then        the direction of the DC-DC converter/charger is changed, and the        holster battery 52 charges the device battery 32, until the        latter reaches the threshold set forth in Paragraph 2        immediately above. In this case the charging will stop.

The circuit diagram in FIG. 9 implements the flow diagram illustrated inFIG. 8. Switch SW1 and SW2 perform the DC-DC converter/chargerinput/output reversing functions and are respectively connected to theinput and the output of DC-DC converter/charger 78. Comparators COMP1and COMP2 detect the state of the handheld electronic device battery 32.When the voltage is above the lower threshold level as inputted from thevoltage divider circuit R2, R3 and R4, COMP2 outputs high. When thevoltage is above the upper threshold, that is in this example 3.8 V,COMP1 turns high. In between, COMP1 will be low and COMP2 will be high.There cannot be a case where COMP1 is high and COMP2 is low.Accordingly, when the battery is near full COMP1 will be high and COMP2will be high enabling gate 84 to provide a high input to the SW3 switchinput 88. The high input closes the SW3 switch and delivers a highoutput to the control input terminal of SW1 and SW2 which moves bothswitches to connect terminal A so that the handheld electronic device 8charges the holster battery 52. When the handheld electronic devicebattery 32 is in its mid range, identified in Paragraph 2 immediatelyabove, the output of COMP1 will be low and the output of COMP2 will behigh providing a low output from the gate 84 to the control inputterminal 88 of switch SW3. The low input opens the switch and openscircuits both SW1 and SW2 to the NO position and no charge sharingoccurs. When the handheld electronic device battery 32 is near empty theoutput of COMP1 and COMP2 will be low causing the control input to SW3from the gate 84 to be high. This high input delivers a low input to thecontrol terminals of switches SW1 and SW2 which connects the switchesSW1 and SW2 to terminal B so that the holster battery 52 charges thehandheld electronic device battery 32. The switching logic is summarizedin the following Table 1.

TABLE 1 State Comp1 Comp2 SW3 SW3 Action Near Full High High High HighDevice charges holster Mid Low High X Low No charge sharing Near Low LowLow High Holster charges Empty deviceThe X in the Table means that no output is provided since the switch SW3under those circumstances is open circuited. Accordingly, the apparatusof this embodiment allows a holster to effectively “steal” small ofamounts of charge over time from a fully charged handheld electronicdevice, and hold it in reserve until required by a user, at the very lowend of the primary battery charge cycle, for an additional day or two ofuse. The device described herein also can reduce the weight of thehandheld electronic device without compromising the battery capacity.

While specific embodiments have been described in detail it will beappreciated by those skilled in the art that various modifications andalternatives to those details could be developed in light of the overallteachings of the disclosure. Accordingly, the particular embodimentsdisclosed are meant to be illustrative only and not limiting as to thescope of the device and method described herein, which is to be giventhe full breath of the appended claims and any or all equivalencethereof.

1. An electronic device comprising: a first battery; charging pads toprovide an electrical connection to a second battery external to theelectronic device; and a charging apparatus configured to charge saidsecond battery when an electrical connection to the charging pads fromsaid first battery under programmed conditions wherein the first batteryonly charges the second battery when the second battery is not fullycharged and the first battery is substantially fully charged.
 2. Theelectronic device of claim 1 wherein the charging apparatus is furtherconfigured to charge said second battery when the second battery is inelectrical connection to the charging pads by delivering a pre-selectedamount of current each time the electronic device is electricallyconnected to the second battery.
 3. The electronic device of claim 1wherein the charging apparatus comprises a switch that connects thecharging apparatus between the charging pads and the first battery upondetecting the second battery.
 4. The electronic device of claim 1wherein the first battery is substantially larger than the secondbattery.
 5. The electronic device of claim 4 wherein the first batteryis approximately 30% larger than the second battery.
 6. The electronicdevice of claim 1 wherein the first battery is substantially smallerthan the second battery.
 7. The electronic device of claim 6 wherein thefirst battery is approximately 30% of the size of the second battery. 8.The electronic device of claim 2 wherein the second battery draws atrickle charge of approximately 100 mAhr or less.
 9. The electronicdevice of claim 2 wherein the pre-selected amount of current isdetermined by the charge level of the first battery.
 10. The electronicdevice of claim 1 further comprising a charging circuit electricallycoupled to the charging apparatus and connectable to an outside chargingsource for charging at least one of the first battery and the secondbattery.
 11. The electronic device of claim 10 wherein the outsidecharging source is a USB port.
 12. The electronic device of claim 1wherein the charging apparatus does not draw current from the firstbattery to charge the second battery when the second battery issubstantially fully charged.
 13. The electronic device of claim 1wherein when the charging pads are in electrical connection to thesecond battery, the charging apparatus is programmed to consume powerfrom the second battery rather than the first battery when the firstbattery is not substantially fully charged.